Electric switch, particularly for use in control of railway signals



Feb. 15, 193.. A. BROWN ET AL 2,10,42

ELECTRIC SWITCHJPARTICULARLY FOR USE IN CONTROL OF RAILWAY SIGNALS FiledSept. 16, 1956' INVENTORS A. BROWN R.H.DUNN AND D.G.MOKIE ATTORNEY IPatented Feb. 15, 1938 UNITED STATES PATENT OFFiE ELECTRIC swrron,

PARTICULARLY FOR USE IN CONTROL OF RAILWAY SEGNALS New York, N. Y.

Application September 16, 1936, Serial No. 101,028

' In Great Britain 9 Claims.

This invention relates to electric switches having parts moved bydifferent means and adapted to close (or open) an electric circuit whenthe parts so moved are in given relative positions.

One feature of this invention consists in an electric switch of the kindreferred to comprising a part-movable by one means, a second partmovable by a second means, a third part movable by both the first andsecond means, and means for closing (or opening) an electric circuitwhen contacts on all three parts are in a given relative position.

Another feature of the invention consists in an electric switch of thekind referred to comprising a first disc carrying contacts and rotatabledirectly by one means, a brush rotatable directly by a second means oversaid contacts and also over contacts on a second disc for completing anelectric circuit, andmeans for rotating said second disc by said firstand. second means in step down ratios that are complementary to oneanother. 7

Yet another feature of the invention consists in an electric switch ofthe kind referred to for controlling an electric circuit according tothe relation between two different series of impulses comprising ratchetwheels adapted to be stepped by the respectiveseries of impulses, innerand outer sun wheels attached to said ratchet wheels, a disc carryingcontacts in said circuit attached to one of said sun wheels, a disccarrying other contacts in said circuit attached to a planet wheelmeshing with each of said sun wheels, and a disc carrying a brushadapted to bridge said contacts to complete said circuit and attached tothe other of said sun wheels.

One application of the invention is to switches used for counting thewheels of a train into and out of a given section of track. The signalsare automatically set to danger when the first wheel enters thesection,- and by means of treadles operated bythe passage of the wheels,or by other means, an impulse is sent to control equipment for thesignals for each wheel entering the track section and another impulsefor each wheel leaving the section. When the same number of outcountingas in-counting impulses has been received a circuit is completed for arelay which restores the signals to clear or allows them to be manuallyrestored. For such application the switch of the present inventionpossesses many advantages. Itallows of a large total count before theincounting portion reaches initial posi- September 27, 1935 (Cl. 200153)and an insulating fibre disc 3 are fixed to a central shaft I,journalled in a suitable frame (not shown). The inner sun wheel 4 of asun and planet gear is secured to the ratchet wheel 2. Planet wheels, ofwhich one only (5) is shown, are rotatably mounted on a spider 6 andengage with the sun wheel 4 and with an outer sun wheel 7. The spider 6is mounted on a sleeve 8 freely rotatable on the shaft I. The sleeve 8carries a second insulating fibre disc 9. The outer sun wheel I is fixedto an outer sleeve Ill freely rotatable on sleeve 3 and carrying aratchet wheel II and an insulating fibre disc I2, which latter carries adouble brush l3 (Figs. 1 and 2) wiping over the peripheries of the discs3 and 9. One terminal of the circuit being controlled is connected to abrush (not shown) wiping on a metal annulus l4 fixed to the insulatingfibre disc l2 on the opposite side from that to which the brush I3 isfixed. The annulus i4 is cut away as shown in Fig. 3 in order to beclear of the rivets fastening brush l3 to disc H. Another brush i9 (Fig.2) is fixed on the side of the disc l2 opposite to that on which theannulus M is fixed, but connected to the annulus by studs passingthrough the fibre. Brush l9 wipes on a metal plate 55 (Fig. 4) fixed tothe insulated 'fibre disc 9. The circuit terminal is thus effectivelyconnected to the plate Iii. The edge of this plate is within; that ofthe fibre'disc except for a projection 20 where it is level therewith.The projection 20 extends over sufficient distance for the brush iii tocontact with it at the initial position and for the distance throughwhich disc 9 is moved by two steps of either of the ratchet wheels 2 orH to each side of the home position. On one side of the disc 3 which isalso of insulated fibre is mounted ametal plate 16 Fig. 6 which has twoprojections 2| and 22 level with the fibre each two steps removed fromhome position, and is connected by metal studs passing through the fibreto a metal annulus l I (see Fig. .5) on the other side of the disc 3. Ametal anratchet wheel 2.

nulus l8 surrounding, but separated from the annulus I! has a projection23 level with the fibre disc 3 at the home position. Circuit terminalsare connected to brushes 24 and 25 wiping over the annuli ll and i8respectively.

In operation, the switch is arranged originally in the home position inwhich the brush l3 rests on the projections 23 and 20 and so completes acircuit between the plate [5 and annulus H3. The relay responding toincounting impulses opcrates a pawl stepping one of the ratchet wheelsand the relay responding to out-countlng impulses operates a pawlstepping the other ratchet wheel in well known manner. It is immaterialwhich ratchet wheel is rotated by in-counting impulses but forsimplicity of description it will be assumed that this is the ratchetwheel 2. On the first in-counting impulse ratchet wheel 2 is rotatedthrough the distance of one tooth. Disc 3 is rotated directly, anequivalent amount, and disc 9 is rotated through the sun wheel t andplanet wheel 5 by a lesser distance. The first impulse is sufficient tobreak the circuit completed in the home position between annulus l8 andplate l5. Further in-counting impulses continue to rotate the discs 3and 9 and on the completion of two steps a circuit is completed betweenthe plate l5 and plate ll. After another step this circuit is broken,and both circuits continue to be broken during further incountingimpulses. The number of revolutions of disc 3 before both discs 3 and 9are back in initial relative positions depends on the relative diametersand numbers of teeth on the sun wheel 4 and planet wheel 5. In order tomeet railway requirements that a total number of 599 wheels can becounted, it has been found satisfactory to provide 60 teeth on the sunwheel 4 and 12 teeth on the planet wheel 5, the diameters being in thesame ratio. Then twelve complete revolutions of the ratchet wheel 2 arenecessary before the discs 3 and 9 return to the same relativepositions. There are 50 teeth on ratchet wheel 2 and therefore 600 stepsare made before this occurs. There are 84 teeth on the sun wheel I andthe diameter of this wheel is in corresponding ratio. When ratchet wheelI l, which is provided with the same number of teeth as ratchet wheel 2,is stepped during the out-counting (in the same direction as ratchetwheel 2) the brushes l3 and sun wheel I are rotated correspondingly,whilst the disc 9 is rotated through the sun and planet gearing in aratio complementary to that by which it was rotated by The circuits areagain closed when the discs 3 and 9 and brushes I3 are again in the samerelative positions and this occurs When the number of out-countingimpulses is the same as those by which ratchet 2 was previously stepped.It is clear, however, that in-counting and out-counting may take placesimultaneously.

It is to be understood that the invention is not limited to the precisedetails shown and described. For example, other gear ratios might beused for counting up to the same total number or up to other differenttotals.

For use in other applications than that specifically referred to theprojections on which brush l3 makes contact could be arranged to close acircuit when the discs are a given number of steps apart. It is alsoclear that the projections and depressions could be interchanged so asto make an electric circuit in all positions but the desired one or few.It is also clear that, as regards certain features of the invention, thetwo sun wheels could be driven continuously instead of step by step.

What is claimed is:

1. An electric switch of the kind referred to comprising a contact partmovable by one means, a second contact part movable by a second means, athird contact part movable by both the first and second means and meansfor closing (or opening) an electric circuit when contacts on all threeparts are in a predetermined relative position.

2. An electric switch as claimed in claim 1 in which the three movableparts are rotatable discs.

3. An electric switch as claimed in claim 1 in which the said first andsecond means cause movements of the said third part in a ratio differentfrom those in which they respectively cause the movements of the firstand second parts.

4. An electric switch of the kind referred to comprising a first disccarrying contacts and rotatable directly by one means, a brush rotatabledirectly by a second means over said contacts and also over contacts ona second disc for completing an electric circuit and means for rotatingsaid second disc by said first and second means in step down ratios thatare complementary to one another.

5. An electric switch as claimed in claim 4 in which said first andsecond discs are attached to inner and outer sun wheels of a sun andplanet gearing driven by said first and second means and said third discis driven by a planet wheel meshing with said inner and outer sunwheels.

6. An electric switch as claimed in claim 4 in which each of said sunwheels is driven in a step by step manner by means of a pawl acting on aratchet wheel attached thereto.

7. An electric switch of the kind referred to for controlling anelectric circuit according to the relation between two different seriesof impulses comprising ratchet wheels adapted to be stepped by therespective series of impulses, inner and outer sun wheels attached tosaid ratchet wheels, a disc carrying contacts in said circuit attachedto one of said sun wheels, a disc carrying other contacts in saidcircuit attached to a planet wheel meshing with each of said sun wheels,and a disc carrying 'a brush adapted to bridge said contacts to completesaid circuit and attached to the other of said sun wheels.

8. An electric switch as claimed in claim '7 in which the said sunwheels are rotated in the same direction.

9. An electric switch as claimed in claim '7 in which the inner one ofsaid sun Wheels and the disc attached thereto is mounted on a shaft, thesaid planet wheel is mounted on a spider carried on a first sleeverotatable on said shaft and the outer of said sun wheels and the disc;carrying the brush are mounted on a second sleeve rotatable on saidfirst sleeve.

ANDREW BROWN. ROLAND HARRIS DUNN. DAVID GORDON MCKIE.

